Gradient-index rod lens made by a double ion-exchange process.

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Gradient-index (GRIN) lenses offer unique optical properties.
• Fabrication of large-diameter GRIN lenses with precise index profiles is challenging.

Purpose of the Study:

• To fabricate gradient-index rod lenses with a parabolic-index profile.
• To evaluate the optical characteristics of these rod lenses.
• To explore the potential for large-sized rod lens fabrication.

Main Methods:

• Utilized a double sodium-silver (Na-Ag) ion-exchange process.
• Fabricated 2-mm diameter rod lenses with parabolic-index profiles.
• Evaluated numerical aperture and minimum focused spot diameter.

Main Results:

• Achieved a numerical aperture of 0.58.
• Obtained a minimum focused spot diameter of 2.5 micrometers (λ=0.63 microm).
• Demonstrated the feasibility of producing large-sized ( >10 mm-diam) rod lenses.

Conclusions:

• The double Na-Ag ion-exchange process is effective for fabricating parabolic GRIN rod lenses.
• The high diffusion rate of silver ions facilitates the production of large-diameter lenses.
• These large-diameter GRIN lenses hold promise for photographic applications.